1. Field of the Invention
The present invention relates to a wrench combination. In particular, the present invention relates to a wrench combination comprising a wrench and a drive member that can be removably mounted into a box end of the wrench.
2. Description of the Related Art
FIG. 1 of the drawings illustrates a conventional wrench combination comprising a wrench and a drive member 2 for driving sockets. The wrench includes a box end including a polygonal inner periphery 1 in which the drive member 2 is mounted. A ball 3 in the drive member 2 is biased by a spring (not shown) to press against the polygonal inner periphery 1 of the box end of the wrench, thereby retaining the drive member 2 in the box end of the wrench.
FIG. 2 illustrates another conventional wrench combination comprising a wrench and a drive member 4 for driving sockets. The drive member 4 includes an annular groove (not labeled) in an outer periphery of an end thereof. An O-ring or C-clip 5 is mounted in the annular groove of the drive member 4. The C-clip 5 is in a compressed state and thus exerts an outward resilient returning force to press against the polygonal inner periphery 1 of the wrench, thereby retaining the drive member 4 in the box end of the wrench.
FIG. 3 illustrates a further conventional wrench combination comprising a wrench and a drive member 6 for driving sockets. An annular groove 70 is defined in a polygonal inner periphery 1 of a box end of the wrench. A C-clip 7 is partially received in the annular groove 70. The C-clip 7 is in an expanded state when the drive member 6 is mounted into the box end of the wrench. An inward resilient returning force causes the C-clip 7 to press against an outer periphery of an end of the drive member 6, thereby retaining the drive member 6 in the box end of the wrench.
However, the above three drive members 2, 4, 6 could not provide a force sufficient to reliably retain the drive members 2, 4, 6 in the box end of the wrench. As illustrated in FIG. 4, when a socket 60 coupled with the other end of the drive member 6 is to be removed, the drive member 6 is pulled outward along with the socket 60 and easily disengages from the box end of the wrench easily, as the C-clip 7 (or the ball 3 in FIG. 1) is in a compressed or expanded state and thus merely provides a retaining force in a direction perpendicular to the pulling direction and as the C-clip 7 (or the ball 3 in FIG. 1) is in sliding contact with the polygonal inner periphery 1 of the box end of the wrench. As a result, the user has to disengage the socket 60 from the drive member 6 and then reinsert the drive member 6 into the box end of the drive member, which is time-consuming, troublesome, and laborsome.
FIG. 5 illustrates still another conventional wrench combination comprising a wrench and a drive member 8. An end of the drive member 8 is mounted in a box end of the wrench. A resilient member 9 is mounted to an end face of the drive member 8 and exerts a relatively large force to a polygonal inner periphery 1 of the box end of the wrench, securely retaining the drive member 8 in the box end of the wrench. However, such a resilient member 9 has a high manufacturing cost and is thus less competitive on the market.
FIG. 6 shows yet another conventional wrench combination comprising a wrench 1′ and a drive member 2′. FIG. 7 is a top view of the wrench 1′ and the drive member 2′ in FIG. 6. The wrench 1′ includes a handle 11′ and a box end 12′ on an end of the handle 11′. The box end 12′ includes a polygonal inner periphery 121′. The polygonal inner periphery 121′ is processed to form an annular groove 120′ that is deeper than the deepest portion of the polygonal inner periphery 121′. A C-clip 3′ is mounted in the annular groove 120′ in a compressed state to exert a force to securely hold an end 21′ of the drive member 2′ by a plurality of protrusions 31′ on an inner periphery of the C-clip 3′. However, the annular groove 120′ is too deep and thus weakens the structure of the box end 12′, as the wall thickness of the box end 12′ becomes relatively small due to provision of the annular groove 120′. The torque capacity of the wrench is significantly reduced.